Open channel implant tools and implant techniques utilizing such tools

ABSTRACT

Implant tools and techniques for implantation of a medical lead, catheter or other component are provided. The implant tools and techniques are particularly useful in implanting medical electrical leads in extravascular locations, including subcutaneous locations. An implant tool for implanting a medical lead may include a handle and a shaft adjacent the handle. The shaft has a proximal end, a distal end, and an open channel that extends from near the proximal end to the distal end, the open channel having a width that is greater than or equal to an outer diameter of the implantable medical lead.

This application claims the benefit of U.S. Provisional Application No.61/902,847, filed on Nov. 12, 2013, the content of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to implant tools and techniques forimplanting implantable medical leads or other implantable components inextravascular locations.

BACKGROUND

Implantable cardiac defibrillator (ICD) systems are used to deliver highenergy electrical pulses or shocks to a patient's heart to terminatelife threatening arrhythmias, such ventricular fibrillation. TraditionalICD systems include a housing that encloses a pulse generator and otherelectronics of the ICD and is implanted subcutaneously in the chest ofthe patient. The housing is connected to one or more implantable medicalelectrical leads that are implanted within the heart.

Traditional ICD systems that utilize transvenous leads may not be thepreferable ICD system for all patients. For example, some patients withdifficult vascular access precludes placement of transvenous leads. Asanother example, children and other younger patients may also candidatesfor non-transvenous ICD systems. Moreover, transvenous leads may becomefibrosed in the heart over time, making lead revision and extractionprocedures challenging.

A subcutaneous ICD system may be preferred for these patients. Asubcutaneous ICD system includes a lead (or leads) that are implantedsubcutaneously in the patient, i.e., between the skin and the ribsand/or sternum of the patient. As such, the subcutaneous ICD mayeliminate the need to transvenous leads within the heart.

SUMMARY

This disclosure provides implant tools and techniques for implantationof a medical lead, catheter or other component, in extravascularlocations including subcutaneous locations. In one example, thisdisclosure provides an implant tool for implanting a medical lead withina patient. The implant tool comprises a handle and a shaft adjacent thehandle. The shaft includes a proximal end, a distal end, and an openchannel that extends from near the proximal end to the distal end, theopen channel having a width that is greater than or equal to an outerdiameter of the implantable medical lead.

In another example, this disclosure provides a method for implanting amedical electrical lead within a patient. The method includes creating afirst incision at a first location on a left side of a torso of thepatient, creating a second incision at a second location near a centerof the torso of the patient, and introducing an implant tool into thepatient via one of the first incision and the second incision. Theimplant tool includes a handle and a shaft adjacent to the handle, theshaft having a proximal end, a distal end, and an open channel thatextends from near the proximal end to the distal end, the open channelhaving a width that is greater than or equal to an outer diameter of theimplantable medical lead.

The method also includes advancing the shaft of the implant tool fromthe incision in which the implant tool was introduced into the patientto the other one of the first incision and the second incision to createa first path between the first incision and the second incision,introducing an implantable medical lead having a distal end includingone or more electrodes and a proximal end including a connectormechanism configured to connect to an implantable defibrillator into theopen channel of the shaft, advancing the implantable medical lead alongthe open channel of the shaft of the implant tool between the firstincision and the second incision, and withdrawing the implant tool fromthe patient while leaving at least a portion of the implantable medicallead in place along the first path between the first incision and thesecond incision.

The method further includes introducing the implant tool into the secondincision at the second location near the center of the torso of thepatient, advancing the implant tool within the patient from the secondlocation to a third location superior to the second location to create asecond path between the second location and the third location,introducing the distal end of the implantable medical lead into the openchannel of the shaft near the handle of the implant tool, advancing thedistal end of the implantable medical lead along the open channel of theshaft of the implant tool from the second incision to the thirdlocation, and withdrawing the implant tool toward the second incision toremove the implant tool while leaving the portion of the implantablemedical lead including the distal end in place along the second pathbetween the third location to the second location.

In a further example, this disclosure provides a method for implanting amedical electrical lead within a patient. The method includes creatingan incision on a left side of a torso of the patient and introducing animplant tool into the patient via the incision, the implant toolincluding a handle and a shaft adjacent to the handle, the shaft havinga proximal end, a distal end, the shaft being curved from the proximalend to the distal end, and the shaft further including an open channelthat extends from near the proximal end to the distal end, the openchannel having a width that is greater than or equal to an outerdiameter of the implantable medical lead. The method also includesadvancing the shaft of the implant tool along a path that generallyfollows the curve of the shaft, the path extending lateral and superiorfrom the incision to a location near an upper portion of a sternum ofthe patient, introducing an implantable medical lead having a distal endincluding one or more electrodes and a proximal end including aconnector mechanism configured to connect to an implantabledefibrillator into the open channel of the shaft, advancing the distalend of the implantable medical lead along the open channel of the shaftof the implant tool from the incision to the location near the upperportion of the sternum of the patient, and withdrawing the implant toolfrom the patient while leaving the implantable medical lead in placealong the path extending lateral and superior from the incision to thelocation near an upper portion of a sternum of the patient.

In some instances, the shaft of the implant tool includes a plurality ofmarkings that identify locations that coincide with locations offeatures of the implantable medical lead when the implantable medicallead is placed within the open channel such that the distal end of thelead is located at the distal end of the shaft. In such cases, themethods herein may include prior to creating the incision(s), placingthe implant tool on the skin of the patient such that the markings ofthe shaft coinciding with locations of features of the medical lead arelocated at a desired location and placing landmarks on the skin of thepatient corresponding with a desired tunneling path to thereby place thefeatures of the medical lead at the desired location.

This summary is intended to provide an overview of the subject matterdescribed in this disclosure. It is not intended to provide an exclusiveor exhaustive explanation of the techniques as described in detailwithin the accompanying drawings and description below. Further detailsof one or more examples are set forth in the accompanying drawings andthe description below. Other features, objects, and advantages will beapparent from the description and drawings, and from the statementsprovided below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram of a patient implanted with an exampleextravascular cardiac defibrillation system.

FIGS. 2A-D are conceptual drawings illustrating an example extravascularimplant tool for implanting a medical lead.

FIGS. 3A-H illustrate an example method of implanting a medical leadusing implant tool of FIGS. 2A-D.

FIGS. 4A-D are conceptual drawings illustrating another example implanttool for implanting a medical lead.

FIGS. 5A-H illustrate an example method of implanting a medical leadusing the implant tool of FIGS. 4A-D.

FIGS. 6A-6G are schematic diagrams illustrating another implant tool forimplanting a medical lead.

FIGS. 7A-7G are schematic diagrams illustrating another example implanttool for implanting a medical lead.

FIG. 8 illustrates a cross-sectional view of an example shaft of animplant tool in conjunction with a distal end of a lead.

FIG. 9 illustrates a cross sectional view of an alternative shaftconfiguration for an implant tool.

FIG. 10 illustrates a cross sectional view of another alternative shaftconfiguration for an implant tool.

FIG. 11 illustrates a longitudinal cross-sectional view of one examplealternative distal end of a shaft of an implant tool that includes abend.

FIG. 12 illustrates a longitudinal cross-sectional view of one examplealternative distal end of a shaft of an implant tool that includes abulb-shape.

FIG. 13 is a schematic diagram illustrating another example implant toolfor implanting a medical lead.

FIG. 14 illustrates a conceptual diagram of a patient implanted with amedical lead using the implant tool illustrated in FIG. 13 and theprocedure using a single incision and a single tunnel.

FIG. 15 is a schematic diagram illustrating another example implant toolfor implanting a medical lead.

DETAILED DESCRIPTION

FIG. 1 is a conceptual diagram of a patient 12 implanted with an exampleextravascular cardiac defibrillation system 10. In the exampleillustrated in FIG. 1, extravascular cardiac defibrillation system 10 isan implanted subcutaneous defibrillation system. However, the implanttools and techniques of this disclosure may also be utilized with otherextravascular implanted cardiac defibrillation systems, such as an acardiac defibrillation system having a lead implanted at least partiallyin a substernal or submuscular location. Additionally, the implant toolsand techniques of this disclosure may also be utilized with otherimplantable systems, such as implantable cardioverter defibrillatorsystems, implantable cardiac resynchronization therapy (CRT) systems(e.g., CRT-P or CRT-D systems), implantable pacing systems, otherimplantable cardiac systems that include combinations of the cardiacsystems above. Likewise the techniques may be used in non-cardiacimplantable systems, including in implantable neurostimulation systems,drug delivery systems or other systems in which leads, catheters orother components are implanted at extravascular locations within patient12. This disclosure, however, is described in the context of animplantable extravascular cardiac defibrillation system for purposes ofillustration.

Extravascular cardiac defibrillation system 10 includes an implantablecardiac defibrillator (ICD) 14 connected to at least one implantablecardiac defibrillation lead 16. ICD 14 of FIG. 1 is implantedsubcutaneously on the left side of patient 12. Defibrillation lead 16,which is connected to ICD 14, extends medially from ICD 14 towardsternum 28 and xiphoid process 24 of patient 12. At a location nearxiphoid process 24 defibrillation lead 16 bends or turns and extendssubcutaneously superior, substantially parallel to sternum 28. In theexample illustrated in FIG. 1, defibrillation lead 16 is implanted suchthat lead 16 is offset laterally to the left side of the body of sternum28 (i.e., towards the left side of patient 12).

Defibrillation lead 16 is placed along sternum 28 such that a therapyvector between defibrillation electrode 18 and a second electrode (suchas a housing or can electrode of ICD 14 or an electrode placed on asecond lead) is substantially across the ventricle of heart 26. Thetherapy vector may, in one example, be viewed as a line that extendsfrom a point on the defibrillation electrode 18 to a point on thehousing or can electrode of ICD 14. In another example, defibrillationlead 16 may be placed along sternum 28 such that a therapy vectorbetween defibrillation electrode 18 and a housing or can electrode ofICD 14 (or other electrode) is substantially across an atrium of heart26. In this case, extravascular ICD system 10 may be used to provideatrial therapies, such as therapies to treat atrial fibrillation.

The embodiment illustrated in FIG. 1 is an example configuration of anextravascular ICD system 10 and should not be considered limiting of thetechniques described herein. For example, although illustrated as beingoffset laterally from the midline of sternum 28 in the example of FIG.1, defibrillation lead 16 may be implanted such that lead 16 is offsetto the right of sternum 28 or over sternum 28. Additionally,defibrillation lead 16 may be implanted such that it is notsubstantially parallel to sternum 28, but instead offset from sternum 28at an angle (e.g., angled lateral from sternum 28 at either the proximalor distal end). As another example, the distal end of defibrillationlead 16 may be positioned near the second or third rib of patient 12.However, the distal end of defibrillation lead 16 may be positionedfurther superior or inferior depending on the location of ICD 14,location of electrodes 18, 20, and 22, or other factors.

Although ICD 14 is illustrated as being implanted near a midaxillaryline of patient 12, ICD 14 may also be implanted at other subcutaneouslocations on patient 12, such as further posterior on the torso towardthe posterior axillary line, further anterior on the torso toward theanterior axillary line, in a pectoral region, or at other locations ofpatient 12. In instances in which ICD 14 is implanted pectorally, lead16 would follow a different path, e.g., across the upper chest area andinferior along sternum 28. When the ICD 14 is implanted in the pectoralregion, the extravascular ICD system may include a second lead includinga defibrillation electrode that extends along the left side of thepatient such that the defibrillation electrode of the second lead islocated along the left side of the patient to function as an anode orcathode of the therapy vector of such an ICD system.

ICD 14 includes a housing that forms a hermetic seal that protectscomponents within ICD 14. The housing of ICD 14 may be formed of aconductive material, such as titanium or other biocompatible conductivematerial or a combination of conductive and non-conductive materials. Insome instances, the housing of ICD 14 functions as an electrode(sometimes referred to as a housing electrode or can electrode) that isused in combination with one of electrodes 18, 20, or 22 to deliver atherapy to heart 26 or to sense electrical activity of heart 26. ICD 14may also include a connector assembly (sometimes referred to as aconnector block or header) that includes electrical feedthroughs throughwhich electrical connections are made between conductors withindefibrillation lead 16 and electronic components included within thehousing. Housing may enclose one or more components, includingprocessors, memories, transmitters, receivers, sensors, sensingcircuitry, therapy circuitry and other appropriate components (oftenreferred to herein as modules).

Defibrillation lead 16 includes a lead body having a proximal end thatincludes a connector configured to connect to ICD 14 and a distal endthat includes one or more electrodes 18, 20, and 22. The lead body ofdefibrillation lead 16 may be formed from a non-conductive material,including silicone, polyurethane, fluoropolymers, mixtures thereof, andother appropriate materials, and shaped to form one or more lumenswithin which the one or more conductors extend. However, the techniquesare not limited to such constructions. Although defibrillation lead 16is illustrated as including three electrodes 18, 20 and 22,defibrillation lead 16 may include more or fewer electrodes.

Defibrillation lead 16 includes one or more elongated electricalconductors (not illustrated) that extend within the lead body from theconnector on the proximal end of defibrillation lead 16 to electrodes18, 20 and 22. In other words, each of the one or more elongatedelectrical conductors contained within the lead body of defibrillationlead 16 may engage with respective ones of electrodes 18, 20 and 22.When the connector at the proximal end of defibrillation lead 16 isconnected to ICD 14, the respective conductors may electrically coupleto circuitry, such as a therapy module or a sensing module, of ICD 14via connections in connector assembly, including associatedfeedthroughs. The electrical conductors transmit therapy from a therapymodule within ICD 14 to one or more of electrodes 18, 20 and 22 andtransmit sensed electrical signals from one or more of electrodes 18, 20and 22 to the sensing module within ICD 14.

ICD 14 may sense electrical activity of heart 26 via one or more sensingvectors that include combinations of electrodes 20 and 22 and a housingor can electrode of ICD 14. For example, ICD 14 may obtain electricalsignals sensed using a sensing vector between electrodes 20 and 22,obtain electrical signals sensed using a sensing vector betweenelectrode 20 and the conductive housing or can electrode of ICD 14,obtain electrical signals sensed using a sensing vector betweenelectrode 22 and the conductive housing or can electrode of ICD 14, or acombination thereof. In some instances, ICD 14 may even sense cardiacelectrical signals using a sensing vector that includes defibrillationelectrode 18, such as a sensing vector between defibrillation electrode18 and one of electrodes 20 or 22, or a sensing vector betweendefibrillation electrode 18 and the housing or can electrode of ICD 14.

ICD may analyze the sensed electrical signals to detect tachycardia,such as ventricular tachycardia or ventricular fibrillation, and inresponse to detecting tachycardia may generate and deliver an electricaltherapy to heart 26. For example, ICD 14 may deliver one or moredefibrillation shocks via a therapy vector that includes defibrillationelectrode 18 of defibrillation lead 16 and the housing/can electrode.Defibrillation electrode 18 may, for example, be an elongated coilelectrode or other type of electrode. In some instances, ICD 14 maydeliver one or more pacing therapies prior to or after delivery of thedefibrillation shock, such as anti-tachycardia pacing (ATP) or postshock pacing. In these instances, ICD 14 may generate and deliver pacingpulses via therapy vectors that include one or both of electrodes 20 and22 and/or the housing/can electrode. Electrodes 20 and 22 may comprisering electrodes, hemispherical electrodes, coil electrodes, helixelectrodes, segmented electrodes, directional electrodes, or other typesof electrodes, or combination thereof. Electrodes 20 and 22 may be thesame type of electrodes or different types of electrodes, although inthe example of FIG. 1 both electrodes 20 and 22 are illustrated as ringelectrodes.

Defibrillation lead 16 may also include an attachment feature 29 at ortoward the distal end of lead 16. The attachment feature 29 may be aloop, link, or other attachment feature. For example, attachment feature29 may be a loop formed by a suture. As another example, attachmentfeature 29 may be a loop, link, ring of metal, coated metal or apolymer. The attachment feature 29 may be formed into any of a number ofshapes with uniform or varying thickness and varying dimensions.Attachment feature 29 may be integral to the lead or may be added by theuser prior to implantation. Attachment feature 29 may be useful to aidin implantation of lead 16 and/or for securing lead 16 to a desiredimplant location. In some instances, defibrillation lead 16 may includea fixation mechanism in addition to or instead of the attachmentfeature. Although defibrillation lead 16 is illustrated with anattachment feature 29, in other examples lead 16 may not include anattachment feature 29. In this case, defibrillation lead 16 may beconnected to or secured to an implant tool via an interference fit aswill be described in more detail herein. An interference fit, sometimesalso referred to as a friction fit, is a fastening between two partswhich is achieved by friction after the parts are pushed together,rather than by any other means of fastening.

Lead 16 may also include a connector at the proximal end of lead 16,such as a DF4 connector, bifurcated connector (e.g., DF-1/IS-1connector), or other type of connector. The connector at the proximalend of lead 16 may include a terminal pin that couples to a port withinthe connector assembly of ICD 14. In some instances, lead 16 may includean attachment feature at the proximal end of lead 16 that may be coupledto an implant tool to aid in implantation of lead 16. The attachmentfeature at the proximal end of the lead may separate from the connectorand may be either integral to the lead or added by the user prior toimplantation.

Defibrillation lead 16 may also include a suture sleeve or otherfixation mechanism (not shown) located proximal to electrode 22 that isconfigured to fixate lead 16 near the xiphoid process or lower sternumlocation. The fixation mechanism (e.g., suture sleeve or othermechanism) may be integral to the lead or may be added by the user priorto implantation.

The example illustrated in FIG. 1 is exemplary in nature and should notbe considered limiting of the techniques described in this disclosure.For instance, extravascular cardiac defibrillation system 10 may includemore than one lead. In one example, extravascular cardiac defibrillationsystem 10 may include a pacing lead in addition to defibrillation lead16.

In the example illustrated in FIG. 1, defibrillation lead 16 isimplanted subcutaneously, e.g., between the skin and the ribs orsternum. In other instances, defibrillation lead 16 (and/or the optionalpacing lead) may be implanted at other extravascular locations. In oneexample, defibrillation lead 16 may be implanted at least partially in asubsternal location. In such a configuration, at least a portion ofdefibrillation lead 16 may be placed under or below the sternum in themediastinum and, more particularly, in the anterior mediastinum. Theanterior mediastinum is bounded laterally by pleurae, posteriorly bypericardium, and anteriorly by sternum. Defibrillation lead 16 may be atleast partially implanted in other extra-pericardial locations, i.e.,locations in the region around, but not in direct contact with, theouter surface of heart 26. These other extra-pericardial locations mayinclude in the mediastinum but offset from sternum 28, in the superiormediastinum, in the middle mediastinum, in the posterior mediastinum, inthe sub-xiphoid or inferior xiphoid area, near the apex of the heart, orother location not in direct contact with heart 26 and not subcutaneous.In still further instances, the implant tools described herein may beutilized to implant the lead at a pericardial or epicardial locationoutside the heart 26. Moreover, implant tools such as those describedherein may be used to implant non-cardiac leads in other locationswithin patient 12.

FIGS. 2A-D are conceptual drawings illustrating an example extravascularimplant tool 30 for implanting a medical lead, such as lead 16 of FIG.1, a catheter, or other implantable component. FIG. 2A illustrates anangled view of implant tool 30. FIG. 2B illustrates a longitudinal sideview of implant tool 30. FIG. 2C illustrates a top view of a shaft ofimplant tool 30. FIG. 2D illustrates a cross sectional view of a distalend of implant tool 30 taken from A-A′ in FIG. 2B. As will be describedin further detail herein, implant tool 30 of FIGS. 2A-D may beparticularly useful in implanting defibrillation lead 16 in patient 12in a subcutaneous, substernal, or other extravascular location.

Implant tool 30 includes a handle 32 and an elongate shaft 34 adjacentto handle 32. Shaft 34 defines an open channel 36 that extends fromhandle 32 to a distal end 38. Open channel 36 may extend the entirelength of shaft 34 from handle 32 to distal end 38. Shaft 24 has alength, labeled “L” in FIG. 2B. The length L of shaft 34 may bedetermined based on the desired tunneling application. For subcutaneoustunneling, shaft 34 may have a length between approximately 5 to 11″ insome instances. However, other lengths may be appropriate for otherdesired applications.

Shaft 34 may have a relatively uniform thickness along the longitudinallength of shaft 34, e.g., along major axis “X” defined by implant tool30. Alternatively, the thickness of the walls of shaft 34 may not beuniform along the length of shaft 34. For example, the walls of shaft 34may have an increased thickness toward distal end 38 compared to theproximal end of shaft 34. The increase in thickness toward distal end 38may enable improved tunneling performance by increasing rigidness orstiffness at distal end 38 or by reducing interference with the tissue.Additionally, the increase thickness of distal end 38 may aid in shapingdistal end to avoid coring, cutting, or puncturing of tissue, pleura,pericardium or other parts of patient 12. In other instances, distal end38 and the proximal end near handle 32 of shaft 34 may have a greaterthickness compared to the middle portion of shaft 34.

In some instances, shaft 34 may include markings 37A-C (collectively,markings 37) that may aid the user during the implant procedure. Forexample, the markings may be placed at locations on shaft 34 thatcoincide with features on lead 16 when lead 16 is placed within openchannel 36 such that the distal end of lead 16 is located at the distalend 38 of shaft 34. In the example, illustrated in FIG. 2C, markings 37coincide with electrodes 18, 20 and 22 of lead 16. In other instances,markings 37 may correspond with other features of lead 16, such asfixation mechanisms (e.g., an anchor sleeve of lead 16). In instances inwhich the markings coincide with features of lead 16, the user mayutilize the marking prior to beginning the procedure to place landmarkson the skin of patient 12. For example, prior to creating incisions, theuser may place the implant tool on the skin of the patient such that themarkings of the shaft coinciding with a desired location of theelectrodes 18, 20 and 22 of lead 16. The user may then place landmarkson the skin of patient 12, such as landmarks corresponding with adesired end point of a tunnel or a desired tunneling path that placesthe features (e.g., electrodes 18, 20, and 22) of lead 16 at the desiredlocation. In this manner, the user may use the markings on the shaft ofimplant tool 30 to be more confident that when insertion tool 30 isrouted according to the landmarks on the skin that the electrodes orother lead features will be in the desired locations. The markings 37may additionally or alternatively provide the user feedback regardingthe distance tunneled, in which case the markings may be located towardthe proximal end of shaft 34. Markings 37 may be laser etched, printed,or otherwise placed on shaft 34 of implant tool 30. Markings 37 may bemade within open channel 36 and/or on the outer surface of shaft 34.

As illustrated in the cross sectional view of distal end 38 of shaft 34,taken perpendicular to the longitudinal length of shaft 34 from handle32 to distal end 38 (e.g., orthogonal to the major axis X defined byimplant tool 30), sheath 34 has a generally C-shaped cross section thatdefines a generally C-shaped open channel 36. In other examples,however, the cross-section of shaft 34 and open channel 36 may be formedinto any of a number of different shapes including, but not limited to,a U-shape, horseshoe-shape, arc-shape, or other shape.

Open channel 36 has a depth, labeled “D” in FIG. 2D. Depth D of channel36 may, in one example, be approximately equal to an outer diameter thelead. In some other instances, the depth D of open channel 36 may beslightly larger than the outer diameter of the lead to provide somemargin. In further instances, open channel 36 may be sized to accountfor the largest portion of the lead, such as a fixation mechanism (suchas tines), an anchoring sleeve, a connector, or other portion of thelead, with or without margin. The margin may allow the user push thelead along open channel 36 without too much interference or friction.

Open channel 36 also includes a width, labeled “W” in FIG. 2D. In oneexample, width W of open channel 36 is greater than an outer diameter ofthe lead (e.g., the diameter of the lead plus a slight margin). Inanother example, width W of open channel 36 is approximately equal tothe outer diameter of the lead such that when the implantable electricallead 16 is placed within open channel 36 there is a slight interferencefit.

In the examples described above, implant tool 30 may be to be used toimplant a particular sized lead such that a different implant tool(e.g., having a different sized open channel 36) may be selecteddepending on the size of the lead to be implanted, which may range from2 French to 11 French. In further examples, a single implant tool 30 maybe designed to deliver leads having a variety of different diameters. Inthis case, the depth D and width W of open channel 36 may be sized fordelivery of the largest diameter lead for which tool 30 is designed.

Shaft 34 may have a relatively uniform thickness along the sides andbottom of the body of shaft 34. In other words, the walls along thesides and bottom of shaft 34 may all have about the same thickness. Inanother example, however, shaft 34 may have thicker walls along thesides of shaft 34 forming open channel 36 than along the bottom of shaft34. FIGS. 9 and 10 illustrate cross sectional views of two alternativeshaft configurations for an implant tool, such as implant tool 30. Inthe example illustrated in FIG. 9, for example, the thickness T1 alongthe sides of shaft 34 forming open channel 36 is greater than thethickness T2 along the bottom of shaft 34. Likewise in FIG. 10, amaximum thickness T3 along the sides of shaft 34 forming open channel 36is less than a maximum thickness T4 along the bottom of shaft 34. Suchconfigurations may add column stiffness and higher torsion stiffness.

Handle 32 may include a guide portion 40 near the end of handle 32 thatis adjacent to shaft 34. Guide portion 40 may be used to guidedefibrillation lead 16 into open channel 36. Alternatively, guideportion 40 may be used by the physician to place a portion of a lead 16within the guide portion 40 and hold the lead in place with a finger. Inthe example illustrated in FIGS. 2A-C, handle 32 is tapered at thedistal end and includes its own channel 42 that extends along thetapered portion of handle 32 from open channel 36. Guide portion 40 maybe particularly useful in instances in which the shaft 34 is fullyinserted into patient 12 via the incision thus making it difficult toaccess open channel 36. In other instances, handle 32 may not include aguide portion or may include a different guide portion. For example,handle 32 may have a guide portion that includes a lumen extending fromthe proximal end of handle 32 to open channel 36 of shaft 34. The lumenallows for passage of defibrillation lead 16 (and connector) throughhandle 32 and guides defibrillation lead 16 into open channel 36 ofshaft 34. In some embodiments, handle 32 may include a grip portion thatis offset from the portion of handle 32 adjacent to shaft 34, such asillustrated and described with respect to FIGS. 7A and 7B.

Elongate shaft 34 of implant tool 30 is formed such that it is stiffenough to be capable of being pushed through the tissue, muscle or otherstructure to form a path through the body. Shaft 34 may be made of ametal, polymer, or other material or combination of materials, e.g.,metal and polymer. One example of a shaft having a combination of metaland polymer would be as shaft having one or more metal rods along thesides of shaft 34 or along the sides and bottom of shaft 34 and theremainder of the shaft being formed of polymer. Such a tool could beextruded, molded, or inserted as part of a manufacturing process andwould provide additional stiffness and malleability to the implant tool.

In some instances, such as when shaft 34 is made of metal or acombination of metal and polymer, shaft 34 may be malleable. Forexample, a user of tool 30 may form shaft 34 to achieve a desired shapeor bend. In this case, an implant kit may include implant tool 30 aswell as bending tool (not illustrated) to aid the user in forming shaft34 of tool 30 to the desired shape or with the desired bend. However,implant tool 30 may be shaped or bent by the user without a designatedbending tool. In instances in which shaft 34 of implant tool 30 ismalleable, the placement of open channel 36 and wall thickness ofimplant tool 30 may be altered to improve ability to be shaped withminimal deformation of open channel 36. In other instances, shaft 34 oftool 30 may not be malleable, e.g., when shaft 34 is made of a moldedpolymer. In further instances, the implant tool may include a pre-formedor pre-shaped shaft 34 (as will be described in more detail with respectto FIG. 17). In this case, shaft 34 may be somewhat flexible while stillbeing stiff enough to tunnel through tissue. The flexibility may allow auser to manipulate the tool slightly to control direction (e.g., steer)of the tunnel. For example, a downward or upward force applied near thedistal end of handle 32 (e.g., adjacent to shaft 34) may result in shaft34 flexing such that distal end 38 of shaft 34 is directed upward ordownward, respectively. Similarly, a force applied in to the left orright near the distal end of handle 32 may result in shaft 34 flexingsuch that distal end 38 of shaft 34 being directed right or left,respectively.

Handle 32 of implant tool 30 may also be made of a metal, alloy,polymer, or other material or combination of materials. Handle 32 andelongate shaft 34 may, in some instances, be constructed of the samematerial. For example, implant tool 30 may be formed of a single,unitary piece of material, such as metal or rigid polymer. In otherinstances, handle 32 and elongate shaft 34 may be constructed ofdifferent materials. In this case, handle 32 and shaft 34 may be formedof separate components that are attached together to form implant tool30, e.g., via a two piece construction. For example, handle 32 may bemade of polymer and shaft 34 may be made of metal and attached to handle32 to form implant tool 30. Example metals or alloys from which handle32 or shaft 34 may be constructed include, but are not limited to,stainless steel, titanium, titanium alloys, nickel-cobalt, andnickel-cobalt alloys. Example polymers may include, but are not limitedto, acetal resin (e.g., DELRIN®), polyether ether ketone (PEEK),polycarbonate, polypropylene composites, and liquid-crystal polymer(LCP). In addition, lubricious fillers and coatings may be used toimprove lubricity during tunneling and lead insertion. Such additives orcoatings include, but are not limited to, siloxane, PTFE, and FosterProPell™. In some instances, implant tool 30 may be a single, unitarypiece of material. For example, implant tool 30 may be a rigid moldedpolymer tool. In other instances, handle 32 and shaft 34 may be formedof separate components that are attached together to form implant tool30, e.g., a two piece construction. For example, handle 32 may be madeof polymer and shaft 34 may be made of metal and attached to handle 32to form implant tool 30 or both handle 32 and shaft 34 may beconstructed of the same material. In some instances, handle 32 may beremoveable as described further with respect to FIGS. 6 and 7.

Distal end 38 of shaft 34 may be shaped to aid in tunneling throughtissue or muscle. For example, distal end 38 of the shaft 34 may betapered, angled, blunt, rounded, pointed, bent or otherwise shaped toenable a user to tunnel through subcutaneous tissue without excessdamage to surrounding tissue, piercing through the skin, or coring ofthe tissue. FIG. 11 illustrates a longitudinal cross-sectional view ofone example alternative distal end 38′ of shaft 34 that includes a bend110. FIG. 12 a longitudinal cross-sectional view of another examplealternative distal end 38″ of shaft 34 that include a bulb 112. Suchshapes may also aid the user in tunneling, particularly throughsubsternal locations as it may reduce the likelihood of penetration ofpericardium or pleural membrane. Distal ends 38′ and 38″ will bedescribed in further detail below with respect to FIGS. 11 and 12.

A user of tool 30 may insert tool 30 into an incision and tunnel distalend 38 of shaft 34 to a desired location. Once at the desired location,the user may deliver an implantable electrical lead, such asdefibrillation lead 16 of FIG. 1, catheter or other implantablestructure in the tunnel or path formed by implant tool 30 by pushing thedefibrillation lead 16 through open channel 36 of shaft 34 and thenremoving tool 30 while leave defibrillation lead 16 in the path createdby the implant tool.

In other instances, the implantable electrical lead 16 may be placedwithin open channel 36 prior to tunneling through the tissue or musclesuch that the tunneling of the path and placement of lead 16 within thepath occurs concurrently. Shaft 34 may also include, in some instances,a lip, hood, shield or other shape or feature that may extend partiallyin front of or over the distal end open channel 36. This may protectlead 16 when lead 16 is placed within open channel 36 during thetunneling procedure. Alternatively or additionally, such a feature mayprovide a distal end that is less likely to puncture the pleura and/orpericardium when tunneling underneath the sternum. Distal end 38′ ofFIG. 11 and distal end 38″ of FIG. 12 illustrate two shapes of thedistal end of shaft 34 that extend at least partially in front of thedistal end of lead 16 when lead 16 is placed within open channel 36.Such shapes may aid in protecting the distal end of lead 16 during thetunneling of the path through the tissue, muscle or other structure ofpatient 12.

FIGS. 3A-H illustrate an example method of implanting a medical lead,such as defibrillation lead 16, using an implant tool, such as implanttool 30 of FIGS. 2A-C. Although FIGS. 3A-H are described in the contextof utilizing implant tool 30 to implant defibrillation lead 16, otherimplant tools described herein may be used to implant lead 16 or anyother implantable medical electrical lead, catheter or other implantablecomponent.

As illustrated in FIG. 3A, a first incision 50 is made at a location onthe side of the torso of patient 12 and a second incision 52 is made ata location near the center of the torso of patient 12. For example,first incision 50 may be made near between the anterior axillary lineand the posterior axillary line on the left side of patient 12 andsecond incision 52 may be made near the xiphoid process of patient 12.However, first incision 50 and second incision 52 may be made at otherlocations on the side and center of the torso, respectively. Forexample, second incision 52 may be offset to the left or right of thexiphoid process of the patient. As another example, second incision 52may be made superior or inferior to the xiphoid process of the patient.Although described herein as first and second incisions, the incisionsmay be made in any order.

Distal end 38 of insertion tool 30 may be introduced into first incision50 (as shown in FIG. 3A) on the left side of patient 12. Implant tool 30is advanced through the subcutaneous tissue from first incision 50 tosecond incision 52 (as indicated in FIG. 3B). Implant tool 30 may beadvanced until distal end 38 exits through second incision 52 or may notexit through second incision 52 but be close enough to second incision52 such that the user may access distal end 38. As described above withrespect to FIGS. 2A-D, the distal end 38 of insertion tool 30 may beshaped to aid in tunneling through subcutaneous tissue from firstincision 50 to second incision 52. For example, distal end 38 of theshaft 34 may be tapered, angled, blunt, rounded, or otherwise shaped toenable a user to tunnel through subcutaneous tissue without damagingsurround tissue or puncturing through the skin of patient 12.

The distal end of lead 16 is introduced into open channel 36 of shaft 34near first incision 50 (as illustrated in FIG. 3C). In one example, thedistal end of lead 16 may be introduced into open channel 36 via guideportion 40 of handle 32. In other instances, the distal end of lead 16may be introduced directly into open channel 36. Defibrillation lead 16is advanced within open channel 36 from first incision 50 toward secondincision 52 until the distal end of defibrillation lead 16 exits secondincision 52 (as illustrated in FIG. 3D). Implant tool 30 is withdrawntoward first incision 50 and removed from the body of patient 12 whileleaving defibrillation lead 16 in place along the path from firstincision 50 to second incision 52 (as illustrated in FIG. 3E). In otherwords, after implant tool 30 is removed, the distal end of lead 16 isextending out of second incision 52, the proximal end of lead 16 isextending out of first incision 50 and the remainder of lead 16 issubcutaneously located in the path or tunnel formed by implant tool 30.

The steps illustrated in FIG. 3A-3C are for illustrative purposes onlyand should not be considered limiting of the techniques describedherein. The user may place defibrillation lead 16 along the path fromfirst incision 50 to second incision 52 in other manners. For example,implant tool 30 may be advanced through the subcutaneous tissue fromsecond incision 52 to first incision 50 (as indicated in FIG. 3B above).In this case, the distal end of lead 16 may be introduced into openchannel 36 of shaft 34 via the distal end 38 of shaft 34 near firstincision 50 and advanced toward handle 32 of tool 30 located near secondincision 52. Alternatively, the proximal end of lead 16 (e.g.,connector) may be placed within open channel 36 of shaft 34 and advancedtoward first incision 50.

Implant tool 30 is then introduced into second incision 52 near thecenter of the torso of patient 12 (as illustrated in FIG. 3E). Implanttool 30 is advanced subcutaneously superior from second incision 52substantially parallel to sternum 28 (as illustrated in FIG. 3F). In theexample illustrated in FIG. 3F, the path followed by implant tool 30 isoffset laterally to the left of the body of sternum 28 and distal end 38of implant tool 30 is positioned near the second rib of patient 12. Sucha path enables defibrillation lead 16 to be implanted such that thedefibrillation energy delivered via electrode 18 returns to the housingelectrode of ICD 14 in a vector that captures the ventricle of heart 26.

However, implant tool 30 may be advanced along other paths. For example,implant tool 30 may be advanced to create a tunnel or path that isoffset from sternum 28 at an angle (e.g., angled lateral from sternum 28at either the proximal or distal end), is offset from sternum 28 on theright side of sternum 28, over sternum 28 or other path depending on theanatomy of patient 12 and/or location of ICD 14. As another example,distal end 38 of implant tool 30 may be positioned further superior orinferior depending on the location of ICD 14 relative to lead 16,placement of electrodes 18, 20 and 22 on lead 16, and other factors.

In other examples, implant tool 30 may be introduced into secondincision 52 and advanced to create a tunnel or path that is notsubcutaneous, but instead is substernal. For example, implant tool 30may be advanced under or below the sternum. Description of otherlocations are provided above with respect to FIG. 1.

The distal end of lead 16 is introduced into open channel 36 of shaft 34near second incision 52. In one example, the distal end of lead 16 maybe introduced into open channel 36 via guide portion 40 of handle 32.The distal end of defibrillation lead 16 is advanced along open channel36 from second incision 52 toward distal end 38 of shaft 34 (asillustrated in FIG. 3G). Defibrillation lead 16 may encounter resistanceupon reaching distal end 38 of shaft 34 as there is no subcutaneous pathpast distal end 38 of shaft 34.

Implant tool 30 is withdrawn toward second incision 52 and removed fromthe body of patient 12 while leaving defibrillation lead 16 in placealong the path from the second incision to the superior location (asillustrated in FIG. 3H). In some instances, the distal end of lead 16may include an anchoring mechanism to fixate the distal end of lead 16in place near the superior location (e.g., near the second or thirdrib). The anchoring mechanism may include tines, a helix, or otheranchoring mechanisms. In other examples, a third incision may be madenear the superior location, e.g., toward the top of sternum 28 proximatethe desired location of the distal end of defibrillation lead 16. Inthis case, implant tool 30 may be advanced subcutaneously from secondincision 52 to the third incision until distal end 38 is proximate toand possibly exits the third incision. The distal end of defibrillationlead 16 would also be advanced through open channel 36 until it isadjacent to the third incision. The distal end of defibrillation lead 16may then be affixed to the desired location proximate the third incisionvia a fixation mechanism separate from defibrillation lead 16, e.g.,sutures, staples, anchor sleeve, or the like, or built intodefibrillation lead 16, e.g., tines, helix or other built in fixationmechanism.

The portion of defibrillation lead 16 proximate second incision 52 mayalso be affixed to the desired location proximate second incision 52 viaa fixation mechanism separate from defibrillation lead 16, e.g.,sutures, staples, anchor sleeve, or the like, or built intodefibrillation lead 16, e.g., tines, helix or other built in fixationmechanism.

A subcutaneous pocket may be created near first incision 50 and ICD 14may be placed within the subcutaneous pocket. A connector ofdefibrillation lead 16 is mechanically coupled to the connector block ofICD 14. The various incision and pockets may then be closed to completethe implant procedure.

The example method of implanting a lead illustrated in FIGS. 3A-H isexemplary in nature and should not be considered limiting of thetechniques described in this disclosure. Other techniques may beutilized using implant tool 30. For example, lead 16 may first beimplanted along sternum 28 as described in FIGS. 3F-H and then tunneledover to the left side of patient 12, e.g., from incision 52 to incision50. As another example, instead of advancing implant tool 30 and thenpushing lead 16 through open channel 36, lead 16 may be placed withinopen channel of implant tool 30 prior to introducing lead inserting tool30 into the incisions such that both the implant tool 30 and lead 16 aretunneled through the tissue at the same time. In a further example, ICD14 may be placed in the upper right pectoral region and lead 16 may beimplanted across the chest and then turn and follow a path inferioralong sternum 28.

In still other examples, a third incision may be made superior toincision 52. Implant tool 30 may be used to tunnel a path from incision52 to the third incision or from third incision to incision 52. Theproximal or distal end of the lead may then be advanced through openchannel 36 either from incision 52 to the third incision or from thethird incision to incision 52 to place the lead within the path formedvia tunneling.

Also, as described above with respect to FIG. 2, prior to creatingincisions, the user may place the implant tool on the skin of thepatient such that the markings of the shaft coinciding with a desiredlocation of the electrodes 18, 20 and 22 of lead 16. The user may thenplace landmarks on the skin of patient 12, such as landmarkscorresponding with a desired end point of a tunnel or a desiredtunneling path that places the features (e.g., electrodes 18, 20, and22) of lead 16 at the desired location. In this manner, the user may usethe markings on the shaft of implant tool 30 to be more confident thatwhen insertion tool 30 is routed according to the landmarks on the skinthat the electrodes or other lead features will be in the desiredlocations.

FIGS. 4A-D are conceptual drawings illustrating another example implanttool 30′. FIG. 4A illustrates an angled view of implant tool 30′. FIG.4B illustrates a longitudinal side view of implant tool 30′. FIG. 4Cillustrates a cross sectional view of a distal end of implant tool 30′taken from C-C′ in FIG. 4B. FIG. 4D illustrates a cross sectional viewof a hook feature taken from D-D′ in FIG. 4B.

Implant tool 30′ can include one or more of the structure and/orfunctionality of implant tool 30 of FIGS. 2A-D (and vice versa).Repetitive description of like numbered elements described in otherembodiments is omitted for sake of brevity. Implant tool 30′ conformssubstantially with implant tool 30 of FIGS. 2A-D except implant tool 30′includes a hook feature 60 toward distal end 38 of tool 30′ to couple toan attachment feature of implantable medical lead 16, such as attachmentfeature 29 illustrated in FIG. 1.

Hook feature 60 is a mechanism by which implant tool 30′ may be attachedto a medical electrical lead. As illustrated in FIG. 4B, hook feature 60define an angled groove that extends into the outer surface of shaft 34and toward distal end 38 of shaft 34. In one example, hook feature 60may be formed by an angled slot on the outer, bottom portion of shaft34. The edges of hook feature 60 may be designed to be rounded, tapered,or otherwise shaped to avoid catching on tissue or muscle when implanttool 30′ is advanced or removed from body of patient 12. Hook feature 60may be designed based on the type of attachment feature 29 of lead 16expected to be implanted using implant tool 30′. Hook feature 60 isdesigned such that when implant tool 30′ is being pulled, attachmentfeature 29 of lead 16 is preferentially pulled into the groove of hookfeature 60.

In the example illustrated in FIG. 4D, the groove forming hook feature60 extends into open channel 34, as illustrated by arc-shaped opening 62along the bottom of open channel 36. However, hook feature 60 may beformed in a number of other shapes. In other examples, hook feature 60may not extend through the thickness of shaft 34 into open channel 34.Instead, hook feature 60 may be an angled radial contoured cut or groovethat is deep enough to catch or accept a portion of lead 26 (such asattachment feature 29), but does not extend all the way into openchannel 36. In some instances, the portion of shaft 34 at which hookfeature 60 is located may have an increased thickness relative to otherportions of shaft 34 to enable hook feature 60 to be formed withoutextending all the way through into open channel 36.

Hook feature 60 may be designed such that when attachment feature 29 oflead 16 is placed within hook feature 60 a portion of attachment feature29 fills opening 62 and/or extends over tab 64 to reduce the likelihoodof catching on tissue or muscle when implant tool 30′ is pulled backthrough the path formed in the tissue.

As will be described in further detail with respect to FIGS. 5A-H, hookfeature 60 may be attached to a lead such that the lead may be pulledthrough a subcutaneous path as insertion tool 30′ is withdrawn from thebody of patient 12. For example attachment feature 29 of lead 16, whichmay be a suture as described above, is placed within hook feature 60,such that the lead may be pulled through a subcutaneous path asinsertion tool 30′ is withdrawn from the body of patient 12. In thismanner, implant tool 30′ may be used to either push a lead through thepath in the subcutaneous tissue (as described above with respect toFIGS. 3A-H) or pull the lead through the path in the subcutaneous tissue(as described below with respect to FIGS. 5A-D). Implant tool 30′ wouldthus provide a single tool that may be used to perform lead insertionvia either technique described above.

FIGS. 5A-H illustrate an example method of implanting a subcutaneouslead, such as defibrillation lead 16, using an implant tool, such asimplant tool 30′ of FIGS. 4A-D. As illustrated in FIG. 5A, a firstincision 70 is made at a location near the center of the torso ofpatient 12 and a second incision 72 is made at a location on the side ofthe torso of patient 12. Although described herein as first and secondincisions, the incisions may be made in any order. For example, firstincision 70 may be made near the xiphoid process of patient 12 andsecond incision 72 may be made near between the anterior axillary lineand the posterior axillary line on the left side of patient 12. However,first incision 70 and second incision 72 may be made at other locationson the center and side of the torso, respectively. In some instances,prior to making incisions 70 and 72, Also, as described above withrespect to FIG. 2, prior to creating incisions, the user may place theimplant tool on the skin of the patient such that the markings of theshaft coinciding with a desired location of the electrodes 18, 20 and 22of lead 16 and place landmarks on the skin of patient 12 correspondingwith a desired end point of a tunnel or a desired tunneling path thatplaces the features (e.g., electrodes 18, 20, and 22) of lead 16 at thedesired location.

Distal end 38 of insertion tool 30′ may be introduced into firstincision 70 (as shown in FIG. 3A) near the center of the torso ofpatient 12. Implant tool 30′ is advanced through the subcutaneous tissuefrom first incision 70 to second incision 72 until distal end 38including hook feature 60 is proximate to and possibly exits from secondincision 72 (as indicated in FIG. 5B). The distal end 38 of insertiontool 30′ may be shaped to aid in tunneling through subcutaneous tissuefrom first incision 70 to second incision 72. For example, distal end 38of the shaft 34 may be tapered, angled, blunt, rounded, or otherwiseshaped to enable a user to tunnel through subcutaneous tissue withoutdamaging surround tissue or puncturing through the skin of patient 12.

Attachment feature 29 of lead 16 is placed within hook feature 60 (asillustrated in FIG. 5C). In some instances, the distal end of lead 16may partially reside within open channel 36 of shaft 34 near distal end38, e.g., adjacent to second incision 72 when attachment feature 29 oflead 16 is placed within hook feature 60. In one example, attachmentfeature 29 may be placed within hook feature 60 from inside channel 36.In another example, attachment feature 29 may be placed over shaft 34 asthe distal end of lead 16 is placed within open channel 36 such that theattachment feature is placed within hook feature 60 from outside ofchannel 36.

Implant tool 30′ is pulled toward first incision 70 pulling lead 16through the subcutaneous path formed during the previous tunneling ofimplant tool 30′ (as illustrated in FIG. 5D). Defibrillation lead 16 nowpartially resides within the subcutaneous tissue from first incision 70to second incision 72 with the distal end of lead 16 extending out offirst incision 70 and the proximal end of lead 16 extending out ofsecond incision 72.

The steps illustrated in FIG. 5A-5D are for illustrative purposes onlyand should not be considered limiting of the techniques describedherein. The user may place defibrillation lead 16 along the path fromfirst incision 50 to second incision 52 in other manners. For example,implant tool 30′ may be advanced through the subcutaneous tissue fromsecond incision 72 to first incision 70. In this case, an attachmentfeature of the proximal end of lead 16 may be placed within hook feature60 and implant tool 30′ may be pull lead 16 from incision 70 to incision72 thereby placing a portion of lead 16 in the subcutaneous path formedduring the previous tunneling of implant tool 30′. Alternatively, openchannel 36 may be sized to provide an interference fit with a connectorof lead 16 or other proximal portion of lead 16 to couple lead 16 toimplant tool 30′ and allow the user to pull lead 16 from incision 70 toincision 72.

Implant tool 30′ is then introduced into first incision 70 near thecenter of the torso of patient 12 (as illustrated in FIG. 5E). Implanttool 30′ is advanced subcutaneously superior from first incision 70substantially parallel to sternum 28 (as illustrated in FIG. 5F). In theexample illustrated in FIG. 5F, the path followed by implant tool 30′ isoffset laterally to the left of the body of sternum 28 and distal end 38of implant tool 30′ is positioned near the second rib of patient 12.However, implant tool 30′ may be advanced along other paths. Forexample, implant tool 30′ may be advanced to create a tunnel or paththat is offset from sternum 28 at an angle (e.g., angled lateral fromsternum 28 at either the proximal or distal end), is offset from sternum28 on the right side of sternum 28, over sternum 38, or other pathdepending on the anatomy of patient 12 and/or location of ICD 14. Asanother example, distal end 38 of implant tool 30′ may be positionedfurther superior or inferior depending on the location of ICD 14,placement of electrodes 18, 20 and 22 on lead 16, and other factors.

In other examples, implant tool 30′ may be introduced into firstincision 70 and advanced to create a tunnel or path that is notsubcutaneous, but instead is substernal. For example, implant tool 30′may be advanced under/below the sternum and/or ribs. Description ofother locations are provided above with respect to FIG. 1.

The distal end of lead 16 is introduced into open channel 36 of shaft 34near first incision 70. In one example, the distal end of lead 16 may beintroduced directly into open channel 36. The distal end ofdefibrillation lead 16 is advanced along open channel 36 from firstincision 70 toward distal end 38 of shaft 34 (as illustrated in FIG.5G). Defibrillation lead 16 will encounter resistance upon reachingdistal end 38 of shaft 34 as there is no subcutaneous path past distalend 38 of shaft 34.

Implant tool 30′ is withdrawn toward first incision 70 and removed fromthe body of patient 12 while leaving defibrillation lead 16 in place (asillustrated in FIG. 5H). In some instances, the distal end of lead 16may include an anchoring mechanism to fixate the distal end of lead 16in place near the superior location (e.g., near the second or thirdrib). The anchoring mechanism may include tines, a helix, or otheranchoring mechanisms.

In some instances, a third incision may be made toward the top ofsternum 28 proximate the desired location of the distal end ofdefibrillation lead 16. In this case, implant tool 30′ may be advancedsubcutaneously from first incision 70 to the third incision until distalend 38 exits through the third incision. The distal end ofdefibrillation lead 16 would also be advanced through open channel 36until it is adjacent to the third incision. The distal end ofdefibrillation lead 16 may then be affixed to the desired locationproximate the third incision via a fixation mechanism separate fromdefibrillation lead 16, e.g., sutures, staples, anchor sleeve, or thelike, or built into defibrillation lead 16, e.g., tines, helix or otherbuilt in fixation mechanism. Alternatively, implant tool 30′ may beadvanced from the third incision to first incision 70, attached to lead16 and withdrawn through the third incision to pull lead 16 along thepath from the first to third incision, e.g., in a manner similar to thatdescribed in FIGS. 5A-D.

The portion of defibrillation lead 16 proximate first incision 70 mayalso be affixed to the desired location proximate first incision 70 viaa fixation mechanism separate from defibrillation lead 16, e.g.,sutures, staples, anchor sleeve, or the like, or built intodefibrillation lead 16, e.g., tines, helix, built-in anchor sleeve orother built in fixation mechanism.

A subcutaneous pocket may be created near second incision 72 and ICD 14may be placed within the subcutaneous pocket. A connector ofdefibrillation lead 16 is mechanically coupled to the connector block ofICD 14. The various incision and pockets may then be closed to completethe implant procedure.

The example method of implanting a lead illustrated in FIGS. 5A-H isexemplary in nature and should not be considered limiting of thetechniques described in this disclosure. Other techniques may beutilized using implant tool 30′. For example, lead 16 may first beimplanted along sternum 28 as described in FIGS. 3F-H and then tunneledover to the left side of patient 12, e.g., from incision 70 to incision72. As another example, instead of advancing implant tool 30′ and thenpushing lead 16 through open channel 36, lead 16 may be placed withinopen channel of implant tool 30′ prior to introducing lead insertingtool 30′ into the incisions such that both the implant tool 30′ and lead16 are tunneled through the tissue at the same time. In a furtherexample, ICD 14 may be placed in the upper right pectoral region andlead 16 may be implanted across the chest and then turn and follow apath inferior along sternum 28. In this example, extravascular ICDsystem 10 may include a second lead the extends from ICD 14 in thepectoral region along the left side of patient 12 such that an electrodeon the second lead may function as an anode or cathode of the therapyvector of such an ICD system.

FIG. 6A-6F are schematic diagrams illustrating another implant tool 80.Implant tool 80 can include one or more of the structure and/orfunctionality of implant tool 30 or 30′ of FIGS. 2A-D and FIGS. 4A-D,respectively (and vice versa). Repetitive description of like numberedelements described in other embodiments is omitted for sake of brevity.Implant tool 80 includes a handle 81 and a shaft 82 removeably coupledto handle 81, the shaft forming an open channel 36. FIG. 6A is aschematic diagram that illustrates implant tool 80 with shaft 82 coupledto handle 81. FIG. 6B is a schematic diagram that illustrates implanttool 80 with shaft 82 removed from handle 81. FIG. 6C is a schematicdiagram that illustrates a cross-sectional view of handle 81 taken fromB to B′. FIGS. 6D-6F are schematic diagrams that illustrate variousviews of shaft 82. FIG. 6G is a cross-sectional view of distal end 86.

As illustrated in FIGS. 6B and 6C, handle 81 may be formed to receiveshaft 82. Handle 81 may, for example, include a lumen 83 to receiveshaft 82. Lumen 83 may be shaped similar to the outer contour of shaft82. In the example illustrated in FIG. 7C, lumen 83 is shapedsubstantially similar to proximal end 84 of shaft 82 illustrated in FIG.7F. Alternatively, lumen 83 of handle 81 may take on a shape differentthan the cross-section of shaft 82, but that would interact with shaft82 to hold shaft 82 in place.

Lumen 83 extends from the distal end of handle 81 toward a proximal endof handle 81. Lumen 83 is configured to couple to the portion of shaft82 placed within lumen 83, which may be either proximal end 84 and/ordistal end 86. Lumen 83 may, for instance, be sized and shaped toprovide an interference fit with shaft 82. As described above, theinterference fit is achieved by friction after the parts are pushedtogether, rather than by any other means of fastening. The interferencefit may, in some instances, be achieved by sizing and/or shaping the twomating parts so that one or the other, or both, slightly deviate in sizefrom the nominal dimension. The interference fit may therefore be viewedas referring to the fact that one part slightly interferes with thespace that the other is taking up. The tightness of the interference fitmay be controlled by the amount of allowance, e.g., the planneddifference from nominal size. Different allowances will result invarious strengths of fit. The value of the allowance depends on whichmaterial is being used, how big the parts are, and what degree oftightness is desired.

In one example, lumen 83 may include a tapered portion toward theproximal end of lumen 83 that has a smaller diameter than the outerdiameter of proximal end 84 of shaft 82. When proximal end 84 of shaft82 is pushed within lumen 83 the outer diameter of proximal end 84 ofshaft 82 interacts with the wall of lumen 83 at the tapered portion toprovide the interference fit. Lumen 83 may likewise be configured toreceive distal end 86 of shaft 82 and couple to distal end 86 via aninterference fit. Although in the example described with respect to FIG.6 the coupling is achieved via an interference fit, handle 81 may becoupled to shaft 82 via any of a number of different interlockingmechanisms. Additionally, other techniques for achieving an interferencefit may be utilized.

Shaft 82 includes a proximal end 84 and a distal end 86. Distal end 86may be shaped to aid in tunneling through tissue or muscle. For example,distal end 86 may be tapered, angled, blunt, rounded, pointed orotherwise shaped to enable a user to tunnel through subcutaneous tissuewithout excess damage to surrounding tissue, piercing through the skin,or coring of the tissue. Distal end 86 may also be shaped to include abend (e.g., such as bend 110 illustrated in FIG. 11), bulb (e.g., suchas bulb 112 illustrated in FIG. 12) or other feature.

Proximal end 84 includes an attachment mechanism 85 configured to coupleto an implantable medical lead, such as lead 16. In the exampleillustrated in FIGS. 6E and 6F, attachment mechanism 85 includes a roundrecess 87 that extends into proximal end 84 and a slit 89 that extendsacross the diameter and into the proximal end 84. Round recess 87 issized to interact with a terminal pin of a connector on the proximal endof lead 16. For example, the diameter of recess 87 may be sized to beequal to or slightly smaller than the diameter of the terminal pin ofthe connector. In this manner, the user of the implant tool may push theterminal pin of the connector of lead 16 into recess 87, which causesslit 89 to slightly expand thereby creating an interference fit with theterminal pin to couple lead 16 to shaft 82. The result is that slit 89elastically deforms slightly to create a force which results in frictionbetween the terminal pin and the walls forming recess 87.

In some instances, attachment mechanism may form part of theinterlocking feature and/or the interference fit. For example, anextension (e.g., similar in size to the terminal pin) may be locatedwithin lumen 85 and may interact with attachment mechanism 85 in asimilar manner as the terminal pin to provide an interference fit of thehandle 81 with the shaft 82. As another example, handle 82 may notinclude a lumen 85, but instead may include an extension (e.g., similarin size to the terminal pin) that extends from the distal end of handle81 and interact with attachment mechanism 85 in a similar manner as theterminal pin to provide an interference fit of the handle 81 with theshaft 82.

In other examples, shaft 82 may include a different type of attachmentmechanism near proximal end 84, such as hook feature 60 described abovewith respect to FIG. 4 or other type of attachment mechanism.Alternatively, shaft 82 may not include any attachment mechanism nearproximal end 84. In still further examples, shaft 82 may include anattachment mechanism at or near both proximal end 84 and distal end 86.For instance, shat 82 may include attachment mechanism 85 at theproximal end 84 and include a hook feature 60 near distal end 86.

Shaft 82 may include any of the variations in thickness described abovewith respect to shaft 34 of FIG. 2. For example, shaft 82 may have arelatively uniform thickness along the longitudinal length of shaft 82or varying thickness along the longitudinal length of shaft 82.Likewise, shaft 82 may have a relatively uniform or variablecross-sectional thickness, such as increased thickness on the bottom orside walls of shaft 82 that form open channel 36. Such description ofwill not be repeated here for sake of brevity.

A user of tool 80 may insert distal end 86 of shaft 82 into an incisionand tunnel distal end 86 from a first incision to a second incision(e.g., as described with respect to FIGS. 3A and 3B or FIGS. 5A and 5B).After tunneling distal end 86 of shaft 82 of tool 80, handle 81 of tool80 may be removed from proximal end 84 of shaft 82 thereby exposingattachment mechanism 85. An implantable medical lead, such asdefibrillation lead 16 of FIG. 1, may be attached to attachmentmechanism 85. In some instances, handle 81 may be placed on the distalend 86 of shaft 82. Whether or not handle 81 is coupled to the distalend 86 of shaft 82, shaft 82 is pulled from the second incision therebycausing lead 16 to be pulled through the tunnel or path formed byimplant tool 80. In this case, the entire shaft 82 of implant tool 80enters the first incision and exist the second incision. In otherinstances, the implantable electrical lead 16 may be introduced intoopen channel 36 of shaft 82 and pushed along open channel 36. As such, auser of implant tool 80 may provide the flexibility to implant lead 16via a variety of different techniques, e.g., via push method, pullmethod, or a combination of push and pull methods. In some instances,handle 81 may not be utilized at all. In such instances, shaft 82 may bea standalone tool without a removeable handle.

FIG. 7A-7G are schematic diagrams illustrating another example implanttool 90. Implant tool 90 can include one or more of the structure and/orfunctionality of implant tool 30 of FIGS. 2A-D, implant tool 30′ ofFIGS. 4A-D, or implant tool 80 of FIGS. 6A-G (and vice versa).Repetitive description of like numbered elements described in otherembodiments is omitted for sake of brevity. Implant tool 90 alsoincludes a removable handle 92. FIG. 7A illustrates implant tool 90 withhandle 92 attached to shaft 91 and FIG. 7B illustrates implant tool 90with handle 92 removed from shaft 91. FIG. 7C illustrates across-sectional view of handle 92 taken from C-C′. FIG. 7D-7G illustratevarious views of shaft 91.

Implant tool 90 includes a shaft 91 having a first end 96 and a secondend 98. Shaft 91 includes a hook feature 60 located toward second end98. Handle 92 may be formed to receive shaft 91. Handle 92 may, forexample, include a lumen 94 to receive shaft 91. Lumen 94 may be shapedsimilar to the outer contour of shaft 91, e.g., as illustrated in FIG.7C. Alternatively, lumen 94 of handle 92 may take on a shape differentthan the cross-section of shaft 91, but that would interact with shaft91 to hold shaft 91 in place. For example, lumen 94 of handle 92 may besemi-circle shaped to accept shaft 91 while leaving channel 36 of thesecond end 98 of shaft 91 open. Lumen 94 may include a taper or othershape to accommodate a taper or other shape of one or both of end 96 and98.

In the example illustrated in FIGS. 7A and 7B, handle 92 is sized andshaped to couple to shaft 91. Lumen 94 may, for instance, have a taperedcircumference within the lumen 94 to provide an interference fit withshaft 91. In other instances, shaft 91 and handle 92 may each includeinterlocking mechanisms configured to mate with one another when shaft91 is inserted within lumen 94 to couple shaft 91 to handle 96. Theinterlocking mechanisms may be on the portion of shaft 91 that is placedwithin lumen 94 and on the walls of lumen 94. Alternatively, theinterlocking mechanism may be outside of the lumen 94 or a combinationthereof. In some instances, hook feature 60 may be the interlockingmechanism or at least part of the interlocking mechanism to couple shaft91 to handle 92. In instances in which an interlocking mechanism is usedinstead of an interference fit coupling, shaft 91 may also include aninterlocking mechanism toward first end 96 to allow handle 92 may becoupled to either end of shaft 91 depending on whether the user ispushing or pulling the tool.

For example, handle 92 may be attached to end 98 of shaft 91 when theuser of implant tool 90 is tunneling through tissue or muscle andplacing lead without pulling the lead through the path created viatunneling (e.g., as described with respect to FIGS. 3A-3H and FIGS.5E-H). Handle 92 may then be removed and reattached to end 96 of shaft91 to pull the lead through the path created via tunneling (e.g., asdescribed with respect to FIGS. 5C and 5D). In one example, the handle92 may be removed and reattached to end 96 after tunneling through thetissue and while the shaft 91 remains within patient 12 (e.g., afterstep 5A and 5B). Alternatively, handle 92 may be removed and reattachedto end 96 prior to steps 5A and 5B in which the user is planning onpulling the lead through the path. This provides the user withflexibility in tunneling and implanting a medical electrical lead.

Handle 92 is illustrated as having a grip portion that is offsetrelative to lumen 94 that receives shaft 91. The offset grip portion mayaid the user in tunneling through tissue, muscle, or the like. In otherinstances, handle 92 may not include and offset grip portion. Insteadgrip portion may be more in-line with the rest of handle 92 as is thecase with handle 82.

Shaft 91 may include any of the variations in thickness described withrespect to FIGS. 2, 4 and 9-12. For example, shaft 91 may have arelatively uniform thickness along the longitudinal length of shaft 91or varying thickness along the longitudinal length of shaft 91.Likewise, shaft 91 may have a relatively uniform or variablecross-sectional thickness, such as increased thickness on the bottom orside walls of shaft 91 that form open channel 36. Likewise, hook feature60 may include any of the characteristics described above with respectto FIG. 4. Such description of will not be repeated here for sake ofbrevity.

FIG. 8 illustrates a cross-sectional view of an example shaft 100 of animplant tool along with a distal end of a lead. Shaft 100 includes anopen channel 102 that includes guides 104A and 104B. Shaft 100 caninclude one or more of the structure and/or functionality of shafts 34,82 and/or 91 of the embodiments described above. In some instances, theimplant tools described above may include one or more features of shaft100. Repetitive description of like numbered elements described in otherembodiments is omitted for sake of brevity.

Guides 104A and 104B extend along an inner surface of the shaft formingopen channel 102 from the proximal end of shaft 100 to the distal end ofshaft 100. Although in the example illustrated in FIG. 8 shaft 100includes two guides 104A and 104B, shaft 100 may include only a singleguide or more than two guides. Guides 104A and 104B may receive aportion of a lead and guide the lead through open channel 102. In theexample illustrated in FIG. 8, a distal end of an example lead is shapedwith protrusions 106A and 106B that fit within guides 104A and 104B. Insome instances, protrusions 106A and 106B may be part of a fixationmechanism such as tines or a portion of a loop, ring or other distallead feature. In the case of tines, for example, the tines may deployupon exiting open channel 102. In addition to or instead of guiding thelead along open channel 102, guides 104A and 104B within open channel102 may also be useful in orientating lead 16 in a specific directionwhen placed, e.g., based on how lead 16 is placed within the guides.

FIG. 13 is a schematic diagram illustrating another example implant tool120. Implant tool 120 can include one or more of the structure and/orfunctionality of implant tool 30, 30′, 80, 90, or the implant tool ofFIG. 8 (and vice versa). Repetitive description of like numberedelements described in other embodiments is omitted for sake of brevity.

Implant tool 120 conforms substantially to implant tool 30, but shaft122 of implant tool 120 is pre-formed or pre-shaped into the curvedshape illustrated in FIG. 13. Shaft 122 may, in one example, have aradius of curvature of between 3 to 5 inches. However, shaft 122 mayhave a radius of curvature that is greater than 5 inches or less than 3inches in other embodiments, e.g., depending on the implant procedurefor which it will be used. In the example of FIG. 13, open channel 36 islocated such that the opening extends along the portion of shaft 122facing the center of curvature. However, in other instances, openchannel 36 may be located such that the opening faces away from thecenter of curvature or elsewhere.

The pre-formed implant tool 120 may allow a user to form a single tunnelfrom a single incision by advancing implant tool 120 to tunnel a pathextending across the torso of the patient and superior along thesternum, advancing lead 16 through open channel 36 of shaft 122, andwithdrawing implant tool 120. FIG. 14 illustrates a conceptual diagramof a patient 12 implanted with lead 16 using the implant toolillustrated in FIG. 13 and the procedure using a single incision and asingle tunnel described above.

In some instances, handle 124 may be a removeable handle (e.g., asdescribed with respect to FIG. 6) and an implant kit may come thehandle, a straight shaft (e.g., shaft 82 or 91), and apre-shaped/pre-formed shaft to provide the user with numerous implantprocedure options as the user can use any of the techniques describedabove to implant defibrillation lead 16.

FIG. 15 is a schematic diagram illustrating another example implant tool130. Implant tool 130 can include one or more of the structure and/orfunctionality of implant tool 30, 30′, 80, 90, the implant tool of FIG.8, and/or implant tool 120 (and vice versa). Repetitive description oflike numbered elements described in other embodiments is omitted forsake of brevity.

Implant tool 120 conforms substantially to implant tool 30, but shaft132 has a slight bend as illustrated in FIG. 15. The bend or curvatureof shaft 132 may be particularly useful for tunneling underneath/belowthe sternum. In particular, the bend or curvature of shaft 132 orientsthe distal end of shaft 132 toward sternum thereby keeping the distalend away from organs in the body cavity during tunneling through thesubsternal space. Open channel 36 is illustrated as opening toward theunderside of the sternum. In other instances, however, open channel 36may open away from the sternum or in another direction.

Although not illustrated in FIG. 15, the distal end of shaft 132 mayinclude an atraumatic tip constructed of a low durometer, flexiblematerial (such as silicone) to reduce the likelihood of puncturing orotherwise damaging the pleura and/or pericardium or others structure inthose locations. In some instances, the atraumatic tip may includeradiopaque markers or the low durometer, flexible material may include aradiopaque additive to allow visualization of the distal end of shaft132. For example, fluoroscopy may be used to determine the shape anddeflection of the distal end of shaft 132 during tunneling.

Various examples have been described. These and other examples arewithin the scope of the following claims.

1. An implant tool for implanting an implantable medical lead within apatient, the implant tool comprising: a handle; and a shaft adjacent thehandle, the shaft having a proximal end, a distal end, and an openchannel that extends from near the proximal end to the distal end, theopen channel having a width that is greater than or equal to an outerdiameter of the implantable medical lead.
 2. The implant tool of claim1, wherein the open channel further includes a depth that is greaterthan or equal to the outer diameter of the implantable medical lead. 3.The implant tool of claim 1, wherein the handle is removable.
 4. Theimplant tool of claim 3, wherein the handle includes a lumen configuredto receive a portion of the shaft, the lumen and shaft creating aninterference fit that couples the shaft to the handle.
 5. The implanttool of claim 3, wherein the lumen is configured to receive at least oneof the proximal end of the shaft and the distal end of the shaft.
 6. Theimplant tool of claim 1, wherein the open channel includes at least oneguide along an inner surface of the shaft forming the open channel, theguide being configured to receive a portion of an implantable medicallead.
 7. The implant tool of claim 1, wherein the implant tool is formedof at least one of a molded polymer and a metal.
 8. The implant tool ofclaim 1, wherein a thickness of the shaft is uniform along a length ofshaft from the proximal end to the distal end.
 9. The implant tool ofclaim 1, wherein a first thickness of the shaft toward the distal end isdifferent than a second thickness of the shaft at the proximal end. 10.The implant tool of claim 1, wherein a first thickness of the shaftalong sides of the shaft forming the open channel is less than athickness of the shaft along a bottom of the shaft.
 11. The implant toolclaim 1, wherein the shaft includes a plurality of markings thatidentify locations that coincide with locations of features of themedical lead when the medical lead is placed within the open channelsuch that a distal end of the lead is located at the distal end of theshaft.
 12. The implant tool of claim 11, wherein the markings identifylocations that coincide with locations of one or more electrodes of themedical lead when the medical lead is placed within the open channelsuch that the distal end of the lead is located at the distal end of theshaft.
 13. The implant tool of claim 1, wherein the shaft is a curvedshaft, the curved shaft having a radius of curvature of between three(3) and five (5) inches.
 14. A method for implanting a medicalelectrical lead within a patient, the method comprising: creating afirst incision at a first location on a left side of a torso of thepatient; creating a second incision at a second location near a centerof the torso of the patient; introducing an implant tool into thepatient via one of the first incision and the second incision, theimplant tool including a handle and a shaft adjacent to the handle, theshaft having a proximal end, a distal end, and an open channel thatextends from near the proximal end to the distal end, the open channelhaving a width that is greater than or equal to an outer diameter of theimplantable medical lead; advancing the shaft of the implant tool fromthe incision in which the implant tool was introduced into the patientto the other one of the first incision and the second incision to createa first path between the first incision and the second incision;introducing an implantable medical lead having a distal end includingone or more electrodes and a proximal end including a connectormechanism configured to connect to an implantable defibrillator into theopen channel of the shaft; advancing the implantable medical lead alongthe open channel of the shaft of the implant tool between the firstincision and the second incision; withdrawing the implant tool from thepatient while leaving at least a portion of the implantable medical leadin place along the first path between the first incision and the secondincision; introducing the implant tool into the second incision at thesecond location near the center of the torso of the patient; advancingthe implant tool within the patient from the second location to a thirdlocation superior to the second location to create a second path betweenthe second location and the third location; introducing the distal endof the implantable medical lead into the open channel of the shaft nearthe handle of the implant tool; advancing the distal end of theimplantable medical lead along the open channel of the shaft of theimplant tool from the second incision to the third location; andwithdrawing the implant tool toward the second incision to remove theimplant tool while leaving the portion of the implantable medical leadincluding the distal end in place along the second path between thethird location to the second location.
 15. The method of claim 14,wherein the implantable medical lead is placed along the first pathbefore the implantable medical lead is placed along the second path. 16.The method of claim 14, wherein the implantable medical lead is placedalong the second path before the implantable medical lead is placedalong the first path.
 17. The method of claim 14, wherein creating thefirst incision at the first location on the left side of the torso ofthe patient comprises creating the first incision between an anterioraxillary line and a posterior axillary line on the left side of thepatient, and creating the second incision at the second location nearthe center of the torso of the patient comprises creating the secondincision near a xiphoid process of the patient.
 18. The method of claim14, wherein advancing the implant tool within the patient from thesecond location to the third location comprises advancing the implanttool from the second location to the third location such that the secondpath is offset laterally to one of the left of the body of sternum andthe right of the body of the sternum.
 19. The method of claim 14,wherein advancing the implant tool within the patient from the secondlocation to the third location comprises advancing the implant toolunderneath a skin and above at least one of a ribcage and a sternum ofthe patient from the second location to the third location.
 20. Themethod of claim 14, wherein advancing the implant tool within thepatient from the second location to the third location comprisesadvancing the implant tool underneath a sternum of the patient from thesecond location to the third location.
 21. The method of claim 14,wherein the shaft includes a plurality of markings that identifylocations that coincide with locations of features of the implantablemedical lead when the implantable medical lead is placed within the openchannel such that the distal end of the lead is located at the distalend of the shaft, the method further comprising: prior to creating thefirst and second incision, placing the implant tool on the skin of thepatient such that the markings of the shaft coinciding with locations offeatures of the medical lead are located at a desired location; andplacing landmarks on the skin of the patient corresponding with adesired tunneling path to thereby place the features of the medical leadat the desired location.
 22. A method for implanting a medicalelectrical lead within a patient, the method comprising: creating anincision on a left side of a torso of the patient; introducing animplant tool into the patient via the incision, the implant toolincluding a handle and a shaft adjacent to the handle, the shaft havinga proximal end, a distal end, the shaft being curved from the proximalend to the distal end, and the shaft further including an open channelthat extends from near the proximal end to the distal end, the openchannel having a width that is greater than or equal to an outerdiameter of the implantable medical lead; advancing the shaft of theimplant tool along a path that generally follows the curve of the shaft,the path extending lateral and superior from the incision to a locationnear an upper portion of a sternum of the patient; introducing animplantable medical lead having a distal end including one or moreelectrodes and a proximal end including a connector mechanism configuredto connect to an implantable defibrillator into the open channel of theshaft; advancing the distal end of the implantable medical lead alongthe open channel of the shaft of the implant tool from the incision tothe location near the upper portion of the sternum of the patient; andwithdrawing the implant tool from the patient while leaving theimplantable medical lead in place along the path extending lateral andsuperior from the incision to the location near an upper portion of asternum of the patient.
 23. The method of claim 22, wherein the shaft ofthe implant tool includes a plurality of markings that identifylocations that coincide with locations of features of the implantablemedical lead when the implantable medical lead is placed within the openchannel such that the distal end of the lead is located at the distalend of the shaft, the method further comprising: prior to creating theincision, placing the implant tool on the skin of the patient such thatthe markings of the shaft coinciding with locations of features of themedical lead are located at a desired location; and placing landmarks onthe skin of the patient corresponding with a desired tunneling path tothereby place the features of the medical lead at the desired location.